1. Field of the Invention
The present invention pertains to the art of washing machines and, more particularly, to an unbalance detection and control system for a washing machine.
2. Discussion of the Prior Art
During operation of a washing machine, it is not uncommon for a tub or spinner of the machine to become unbalanced due to the particular distribution of a load of clothes therein. When the tub is rotated at a relatively high speed during an extraction phase of an overall washing cycle, an unbalanced condition can cause considerable vibrations of the entire machine. Since excessive vibrations can be detrimental to the continued reliability of the machine, it is known in the art to provide a vibration detection system for sensing an actual or incipient unbalance condition and for altering the operation of the machine when a predetermined threshold is reached. Typically, known systems function to either reduce the rotational speed of the clothes tub or entirely shut down the machine to counteract an unbalance condition.
In the art, various different vibration detection systems have been employed. For instance, it has been known to employ switches, such as mercury or micro switches, which are engaged when excessive vibrations are encountered. Activation of these switches is relayed to a controller for altering the operational state of the machine. Other known systems provide rather complicated electronic sensing systems to perform a corresponding function. In any event, the prior devices are designed to sense vibrations in only a limited number of planes or directions. More specifically, these known arrangements sense vibrations in either one or two planes. Therefore, at best, these unbalance detection systems are only designed to determine excessive vibrations in a maximum of four directions.
Sometimes it would be beneficial to sense an unbalance condition in at least one additional plane or direction. Expanding the planes or directions can be particularly important in connection with horizontal axis washing machine arrangements. That is, known unbalance sensing systems utilized in horizontal axis washing machines sense excessive vibrations in generally only vertical and/or horizontal planes. However, it has been found that a potentially damaging condition can be created based on excessive fore-to-aft movements of the spinner. Therefore, there exists a need in the art for an unbalance detection system for a washing machine, particularly a horizontal axis washing machine, which can sense an unbalance condition in three, substantially perpendicular planes and at least five directions. Furthermore, there exists a need for an improved unbalance detection system which is simple in construction and operation, so as to be reliable and cost effective.
A washing machine constructed in accordance with the present invention incorporates a system for controlling either an actual or incipient unbalance condition in a reliable, accurate and cost effective manner. More specifically, the present invention is directed to an unbalance detection system for a washing machine, particularly a horizontal axis washing machine, which can sense excessive vibrations in at least five directions, along three substantially perpendicular axes.
In accordance with the invention, the unbalance detection system preferably incorporates a single switch, the position of which can be altered based on excessive vibrations in any one of multiple planes or directions. In the most preferred form of the invention, a switch is fixedly secured relative to a cabinet portion of the machine and has an associated actuator which is attached to a mounting support through a plurality of springs. The springs tend to position the actuator in a neutral condition which is reflective of a balanced operation state for the machine.
The actuator also includes a shank portion arranged proximate a component of the machine which would tend to vibrate excessively during an unbalanced operating condition. In the preferred embodiment, the shank portion extends through a bore formed in a bracket element provided on a counterbalance weight unit attached to an outer tub of the washing machine. Since the shank portion extends through the bore, it is surrounded by the bracket element and therefore can be engaged upon any excessive movements of the outer tub in various directions. In a horizontal axis washing machine, these directions include up, down and side-to-side movements of the outer tub. In addition, the shank portion preferably carries at least one cross pin which can be engaged to further shift the actuator upon excessive unbalance movement in a generally fore-to-aft direction. Once an unbalance condition is sensed, a signal is relayed to a controller for altering the operation of the machine to counteract system imbalances.
Based on the above, it should be readily apparent that the invention provides for a relatively simple, inexpensive unbalance detection assembly which is sensitive to out-of-balance conditions in a multitude of directions and planes. In any event, additional objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention, when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.